Heads up: don't play as the Plant in Mob Smash, allegedly it can corrupt your save or something.

I read All-Star Mode specifically.

Also there's some weird glitch if you use his final smash in Classic Mode. I've experienced it. It seems to push you off the stage and "K.O." you, bringing up the continue screen, even though you might still be on the screen alive and well.

I've had a surprising amount of fun with the spirits but that's probably because I get a lot of the references they use for the fights. Dark Realm is a lot more bulls**t than the Light Realm, and the final map is surprisingly unmemorable aside from, like, Wedding Bowser or Isaac and it's actually kind of short. But I wouldn't have a problem with playing on a higher difficulty if the DLC fighters add more to it when they're released (unlikely, but I'm willing to dream). Still have to play Classic and tear through the Challenges if I can.

Spoiler.

The part where you play as Master Hand knocking around minions is SO GREAT though and the fight with Galeem and Dharkon does not disappoint in the slightest.

^Unless there's an expansion to WoL that comes with the Fighter Pass or something, I don't think they're gonna add anything to it other than just appearing on your roster. Piranha Plant did come with a Classic route, though, so the next 5 should as well.

Cleared out every spirit from the map, awakened every fighter, & freed both Hands. Only 4 battles away from 100% completion. Also only 4 spaces left on the skill tree that I probably won't be able to fill until New Game+. And I've only just now realized I can visit all the shops from the pause menu instead of having to walk the whole map to each of them.

Yeah, for NG+ you should just equip your strongest Spirits and brute force through everything unless you really want Snacks for some reason. Ignore hard fights and just go for character unlocks/bosses for the most Spirit Points.

Boom. Did it. The Master Hand crushing an army of spirits fight (that was so freaking cool), & all 3 endings. Then went ahead & started NG+ so I could finish off the skill tree.

Observations:
Simon with all the weapon & special move upgrades utterly dominates poor slow Giga Bowser; just spam axes to win.
The ascent to the boss rush was actually harder than the boss rush itself, & even then the only really annoying part was the buzzsaw push-ins.
Possibly the best reward you get for completing the game is finally getting to change the menu music.